Distilling column and the like



1950 G. A. DALlN 2,520,494

DISTILLING COLUMN, AND THE LIKE Filed July 23, 1948 2 Sheets-Sheet l INVENTOR, GEORGE A. DALIN Patented Aug. 29, 1950 UNITED STATES PATENT OFEKIE 16 Claims.

This invention relates to columns or towers in which it is desired to maintain a predetermined temperature condition for distillation, condensation, or chemical reaction purposes.

In the operation of a fractionating or distilling column, it is often important to prevent heat exchange between the vapors in the column and the surrounding atmosphere, so that the column can be operated adiabatically or with a more or less uniform temperature gradient between inlet and outlet. Provision of insulation or a vacuum jacket around the column reduces the heat losses, but such expedients do not always suflice, particularly when the column throughout is small, as in laboratory apparatus, or when even small heat losses cannot be tolerated in larger columns. In such cases, it has been the practice to heat the column externally to offset any heat losses, and it is with externally heated apparatus of this type that the invention is especially concerned.

It has been proposed to maintain the desired temperature conditions in distilling columns, and the like, by surrounding the column with a jacket and heating the intervening enclosed space electrically by one or more wires disposed around the heating jacket from top to bottom. Such apparatus as constructed heretofore leave much to be desired, largely because they do not lend themselves to easy and precise adjustment of both the amount and the distribution of external heat supplied along the column, which adjustments often are critical and are needed during the distilling operation as well as in changing over from one operation to the next. Control of the total amount of heat can be had quite easily by external regulation of the current supplied to the electrical heating element or elements. However, in prior apparatus of this type the facilities for adjusting the distribution of the total heat supply along the column are limited, in spite of the fact that a simple means for making such adjustments accurately and in small increments over a wide range is recognized as highly desirable.

Another difficulty with prior apparatus of this type is in determining the temperature conditions in the annular space between the heating jacket and the column. In some instances, it has been necessary for this purpose to mount thermometers at the desired locations in the annular space. Due to the inaccessibility of this space, which is closed at the top and bottom by supports for the column and jacket, it is a troublesome procedure to change the location of the thermometers in order to determine the proper heat input along different parts of the column or for any other purpose.

The principal object of the present invention is to provide a distilling column, or the like, which overcomes the above-mentioned difiiculties inherent in prior apparatus of this type.

In order to realize the advantage of visibility of the column, it is the practice to use glass as the material for the heating jacket and also for the usual draft jacket surrounding the heating jacket. Since the jackets extend continuously around the column and are fragile, access to the heating wire between the jackets, and to the temperature indicators between the heating jacket and the column, has been had only at the top and bottom of the jackets where they are closed in the assembled apparatus by the supports or end caps, which have openings for the conductors leading to the heater. This characteristic of the prior apparatus, inaccessibility of the heater and indicators except from the top and bottom of the jackets, imposes limitations upon the apparatus, as pointed out above, but has been regarded as necessary in view of the nature and arrangement of the jackets.

I have discovered that in apparatus of this type the heating wire and indicators can be made accessible from the side of the apparatus which, at the same time, can be made sufficiently strong even though the jackets are constructed of glass. According to the invention, the heating jacket carries a series of turns of heating wire energized by one or more conductors extending outwardly from the side of the heating jacket and, if a surrounding draft jacket is used, through an opening or vertical slot in the latter. Also, the heating jacket may be provided with a series of vertically spaced openings between the wire turns and through which temperature indicators can be inserted into or removed from the space around the column. Thus, the wire turns on the heating jacket can be easily tapped from the side of the apparatus at any desired vertical location along the jacket so as to enable variations in the heat distribution, and the indicators can be adjusted vertically in the heating jacket in accordance with changes in the heat distribution.

In the preferred construction, the heating jacket is provided with a vertical slot which receives a retaining post aligned with a vertical slot in a draft jacket. The post is made of insulating material adapted to withstand the high temperatures; and it holds the wire turns in position on the heating jacket and is held in its slot by the tension in the wire. In this way, even though the heating jacket is made of glass, it has sufficient strength and resistance to breakage in spite of the slot. The wire turns extending across the face of the retaining post are readily accessible through the slot in the draft jacket. Also, by providing the retaining post with openings oifset from the wire turns, suitable temperature indicators can be easily inserted at the desired locations in the space between the heating jacket and the column.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

Fig. 1 is a vertical sectional View of one form of the new apparatus, the view being taken on the line l! in Fig. 2;

Fig. 2 is a horizontal sectional view of the apparatus, taken on the line 2-2 of Fig. 1;

Fig. 3 is an elevational view of the upper part of the retaining post illustrated in Figs. 1 and 2, showing the manner in which the heating wire is held by the post;

Fig. 4 is an enlarged vertical sectional view of a modified form of the temperature indicating device;

Fig. 5 is a schematic View of the apparatus, showing the electrical connections, and

Fig. 6 is a horizontal sectional view of part of a modified form of the apparatus.

For illustrative purposes, the apparatus is shown in a form suitable for laboratory use in fractional distillation. However, it will be understood that the invention can be utilized in production installations and for purposes other than distillation, such as effecting chemical reactions under controlled temperature conditions, in which case the column will constitute a chemical reactor tube. In fact, the apparatus can be used to control the heating of any object within the heating jacket.

In the apparatus as illustrated, the distilling or fractionating column I8 is of the usual hollow cylindrical form made of glass and adapted to receive at its lower end the volatile components from a flask (not shown) in which the mixture to be distilled is boiled. The volatile components passing'up through the column are withdrawn at the upper end through a suitable outlet (not shown). A cylindrical heating jacket H surrounds the column and in turn is surrounded by a cylindrical draft jacket [2. As is customary in apparatus of this type, the two jackets are made of glass, which allows the operator to see the interior of the column during the distilling operation. The parts It, H and [2 are heid in concentric relation by top and bottom caps 53 and I l mounted above the flask on a suitable support (not shown). Each cap has concentric grooves l 5 for receiving the adjacent ends of the two jackets, and also has a central opening for receiving a removable collar l6 closely surrounding the column, the collars [6 having peripheral flanges resting upon the surrounding caps. Thus, the column can be easily replaced by one of chiferent sizeby substituting collars having openings of different size.

The draft jacket 12 has a vertical slot 92 opposite a vertical slot H in the heating jacket, the slots extending from the top to the bottom of the jackets. Slot i l is somewhat wider than slot 12 and receives a retaining post Iii made of asbestos or other electrical insulating material capable of withstanding the temperatures encountered in the operation. .Ihe post is fitted couple assembly comprisingapair of ceramic. 76

closely in the slot H and projects outwardly therefrom toward the draft jacket and also inwardly into the annular space 59 between the column and the heating jacket. The interengaging edges of the post and the slot l! lie in vertical planes extending radially from the axis of the column, for a purpose to be described presently.

A heating or resistance wire has a series of turns 26 carried by the heating jacket, including the post it. The wire is wound closely around the jacket H in a spiral, the ends of the wire being connected to terminals 21 mounted on the post 18 near the top and the bottom. The retaining post is provided with means for holding the turns 20 in vertically spaced relation, such means as illustrated being transverse detents 22 on the outer face of the post forming transverse grooves l8 for receiving the turns. It will be apparent that the tension in the wire turns serves to hold the post in its slot I l Mor particularly,

when the post is inserted in the slot and the heating wire wound around the jacket II, with the turns in the grooves I6 the tendency of the wire turns to force the edges of the slot together is exactly counterbalanced by the tendency to force the post into the slot and spread the edges. It is for this reason that the cuts forming the interengaging edges of the post and the slot ll are radial, sinc the post then acts, insofar as balancing these forces is concerned, as if it were an integral part of the glass jacket, whereby breakage of the glass is avoided. A further advantage is that if thewidth of the slot ll is not exactly as planned, the tapered cross-section of the post makes it possible to compensate by seating it farther into or out of the slot. To compensate for variations in the width of the slot from top to bottom, it may be desirable to use two ormore sections of post arranged end to end in the slot. Each section will then seat itself at the appropriate depth, thereby giving sufficient support along the glass jacket to prevent collapse.

In regard to the radial cuts forming the verti-' cal slot I l in the heating jacket, it is well known that a glass tube as usually made is non-uniform in thickness, diameter and cross-sectional shape, and is not exactly straight. However,-if the radial cuts are made to intersect an arbitrary straight axis approximating a true axis, and the subtended angle between the slot edges is the same as the extended angle between the tapered edges of the retaining post, the post'will seat in the slot along its entire length even though the glass tube is misshapen.

In its outer face, the post l8 has a vertical groove 18* which is of sufficient width to receive adjustable contacts 24 for energizing the heating wire. As shown in Fig 5, there is a pair ofsuch contacts, each of which may be a standard alligator clip (Fig. 1). deep to allow the jaws'of the clip to grasp one of the wire turns 20, without interference from the post.

The retaining post it is also provided with holes, opening into the groove 13*, for receiving oneor more temperature indicating devices. As shown, I employ three such devices 26, one. for each of the heating sections-20 20 and 28 into which the heating wire is divided by the two adjustable.

contacts 24 (Fig. 5). Each indicating devicel'o may conveniently be in theform of a thermoinsulators 21, 21 projecting from holes in the The groove it is sufficiently best outwardly through spaces between the wire turns 20. The insulator 21 projects inwardly into the annular space [9 where it terminates near the distilling column l0, and it contains a Constantan wire 28 connected at its inner end to a coil spring 29 at a junction 30, as by brazing or soldering or in some other manner whereby the temper of the wires is retained. The spring 29, madeof iron wire, is coiled around the insulator 27, and its outer end is connected to a Constantan wire 28 extending through the insulator 21%. With this construction, the spring 29 urges the junction 38 against the column I6, so that by connecting a galvanometer 3| (Figs. 4' and 5) across the wires 28 and 28 outside the apparatus, the temperature differential across the space l9 can be easily determined. Also, the spring 29 enables the junction 30 to be retracted from the column, either by sliding of the wire 28 in its insulator 2'! or by sliding of insulator 21 in the post, which facilitates replacement of the distilling column IO; and the junction 31 will auto matically position itself against the column regardless of its diameter.

' -If desired, the upper insulator 2? may contain a second wire 28 of iron located in a separate passage in the insulator and connected at its inner end to the junction 38, as shown in Fig. 4. In this way, by connecting a milli-voltmeter 32 (Fig. 4) across the wires 28 and 23*, the actual temperature of the column can be determined where it is engaged by the junction 35 Referring now to the wiring diagram, Fig, 5, the terminals 2! of the heating wire 28 are connected to conductors es and 35, respectively,

which in turn are connected through a variable transformer (or rheostat) 36 to a current source 31. The upper and lower contacts 24 are connected through leads 26 and 26 to the conductors 34 and 35,.respectively, and are adjustable vertically along the heating jacket, such adjustment being permitted either by the flexibility of the leads 24 and 2 t or by sliding of the leads along the conductors 36 and 35. Thus, the contacts divide the heating wire into upper, intermediate, and lower heating sections 20, 26 and 29, respectively, the three sections being connected in parallel across the current source. This arrangement permits quick and easy adjustment not only of the total amount of heat from wire 26 (by adjusting of the transformer or rheostat 36) but also of the distribution of the heat along the column within the jacket 5 i.

For example, by moving the lower contact 24 downwardly so that it'engages a lower turn of wire 20, the resistance of the lower section 26 is decreased. as well as the vertical extent of this section. Since the heat output of this section is EZ/R and E is fixed by the variable transformer or rheostat'36, then the heat output is inversely proportional to R. Thus, decreasing R by decreasing the number of turns in section 20 increases the heat output in section 20. Conversely, the resistance and vertical extent of the intermediate section 28 is increased, but its heat output is decreased. By raising the lower contact 24, these changes in the output and vertical extent of the respective sections 2t and 253 are reversed. Similar adjustment of the vertical position of the upper contact 24 causes similar changes in the output and vertical extent of the respective heating sections 23 and 26 By raising or lowering the contacts 2 equal amounts, the top and bottom heating sections 28 and 20 can be adjusted to vary their. respective heat outputs and vertical extents, without afiecting the intermediate section 20? except to change its vertical position. Thus, the distribution of the heat output can readily be varied by small steps over a wide range, which is a highly advantageous feature in apparatus of. this type, as is well known in the art- The contacts 24 may, of course, be of diiferent form than that shown in Fig. 1. For example, they may be sliding contacts, as shown at 38 in Fig. 6, in which case the vertical groove it in the post may be reduced in depth or eliminated. As shown in Fig. 6, each contact 38 is carried by a slide 39 mounted in the vertical slot l2 in the draft jacket. By sliding the contacts up and down on their respective slides 39, the distribution of thejheat may be varied, as previously described. The contact should be long enough to make contact with any wire turn before breaking contact with an adjacent turn, thus avoiding sparking.

The location of the thermocouples 26 may be varied according to the adjustments of the heating sections 203 2t and 2t", or as otherwise desired, by inserting them in selected holes spaced along the retaining post. Usually, it is desirable to position a thermocouple at the central part of each heating section. By use of the difierential thermocouples, it is a relatively simple matter to determine the proper adjustment of the contacts 24 (33) for the necessary heat output from each heating section inorder to obtain the desired temperature conditions along the column, as indicated by the thermocouples. Determination of the temperature differentials at the several thermocouple locations can be facilitated by use of a selector switch at! (Fig, 5) having an arm 4! en gageable selectively with contacts 42*, 82 and 42 connected to one side of the upper, intermediate and lower thermocouples 26, respectively. The other side of each thermocouple is connected to a common wire 63 leading to one side of the galvanometer 3!, the other side of which is connected to the arm Thus, engagement of arm with any of the contacts 12 e2 e2 connects the corresponding thermocouple across the galvan-ometer, the reading of whichindicates the temperature difierential.

It will be apparent that in the new apparatus, the turns of the heating wire are readily accessible from the side of the apparatus along the entire height of the heating jacket, and because of this feature I am able to provide for the aforementioned adjustment of the heat distribution in a simple and effective manner. Also, by virtue of this feature, the wire turns may be arranged to form a plurality of separate heating elements which can be eneergized and deenergized automatically under control of respective thermostats extending into the space l9, thereby maintaining the desired temperature condition. The vertical slot in the outer or draft jacket 12 need be only of a width sufficient to accommodate the contacts 24 or the slides 39, so that the usual functioning of the draft jacket is not impaired. The column it can be operated in the manner which is customary in distilling apparatus (or in a chemical reactor) the adjustable contacts and the thermocouples, however, enabling easy regulation of the temperature conditions.

The end caps 83 and It may, if desired, be provided with annular grooves E5 on both faces, so that the heating and draft jackets can be stacked to accommodate columns of any length. The

column ill may be supported by a bulge in its upper or lower portion overlying the upper or 7 lower. collar 1 6 it will ibe understood: that the apparatus 1 issusceptible "of other t modifications within'ithe scope 'ofiilthe invention.

Lclaim:

i 1. In an apparatus of themharacten described, having a: column,v a heating- 3 acket =surrounding the column and spaced therefrom, and azdraft jac'ketsurrounding the ii-eating jacketa',n"cl=spac'ed therefrom, the improvement "which comprises a heating Wire having a se'ri'essof turns car-fied by the heating jacket and spaced verticallyfrom each other, the draft jacket having a vertical slot through which the turns are-accessible, an a'djustable' contact extend-ing through theslot'and engaging-one of the wire turns, the contact dividing thewire into upper andlower-heatingaections and being adjustable vertically irrth'e slot to engage 'difierent turns of the wire and-thereby vary'the resistances andthe vertical-extents of the'respe'ctive sections; a=current'source, and electrical connections; including the adjustable contact, for-connecting said sections in parallel to the current source.

The improvement asdefined in claim 1, in which the heating jacket has a recess opposite the draft jacket slot and over which the wire extends, the recess beingadapted to receive part of said contact.

"3. The improvement as defined in claim 1, in which the heating jacket has an opening opposite the draft jacket slot and located'between adjacent turns of the wire, and a temperature indicating device extending through the slot and the opening into the space between the heating jacket and the column.

4. The-improvement as defined in claim 1, in which'the heating jacket has a vertical slot opposite the draft jacket slot, and a retaining post disposed in the heating jacket elot-and-engaging the wire turns to hold them invertically spaced relation.

5. Inan apparatus of the character described, having a column, a heating jacket surrounding the column and spaced therefrom, and a plurality of turns of heating wire carried by thejacket for heating'the space between the jacket and the column, the improvement which comprises an insulating retaining post disposed within said turns and holding the turns in spaced relation on thejacket, the, post having a plurality of holes eachaligned with a lateral opening in the jacket for inserting a temperature indicating device through thepost and jacket intothe space between the jacket and the'column.

'6. The improvement as defined in .claim 5,in' which the-heating jacket is slotted verticallyto form said lateral opening, thepost being fitted into the vertical slot to give mechanical support to the jacket.

7. In an apparatus of the character described, having a column, a heatingjacket surrounding thecolmnn and spaced therefrom, and a' heating wirecarried'bythe jacket for heatingthe space between the jacketv and the column, the improvement which comprises a retaining post of insulating material forming part of the jacket wall, the jacket having a vertical slot in which the post is fitted and providing access to the interior of the jacket the. heating wire including. aplurality of turns extending at least partly aroundthe exterior--01 the jacket, means on the post for holding said turns in verticzztlly spacedrelation, a contact for energizingwtheWire andadjustable along the post to-engage different turns of the wire, and a 8 draftjacketsurrounding the heating-gakt send spaced 'ltherefrom, the urarwaekeenavmgave;- tic'al slot opposite s'aid first slot and through which th'e 'adjustable contact extends. I

8. The provement-as' d'cfined in claimfl, 111 which the wire turns extend across the outer face of the post to hold'the post in the slet.

*QYIhe imprQVemeIit as defined inc1aim"7 in which the post and the slot have interengaging edges ,cachedge lying in-a vertical plane extending radially from the column. 7

10. In an'a'pparatus of the character described, having a column, aheatihgjabket surrounding the "column and spacedtherefrom; and" at-heating wire carried'by the jackefifor -heatin'g the space between the jacket and the column, the improvement which-comprises a retaining post of insulating materiaircrming. partor the jacket wan, the jacket having a vertical slot in which the, post isxs ated,meneanngmre including a plural it'j of turns extending at least partly around the exterior .of the jacket, means -on the --post 5 for holding saidturns in vertically spaced-relation, and a contactfor energizing the wire andadjustable along the post to engage different turns-of the wire, the post and the. slothaving interengagingedges, each edge lying ina verticalplane extending radially from thecolumn, the wire turns extending under tension across the outer faced the post to hold the post in the slot, whereby the tendency of the-wire to: force theslot edges-together is counterbalanced by the tendency of the wire to force the post into'the slot and' spread the: slot-edges.

'11. In an apparatus of-the character described, having :a 'column, aheating jacket surrounding the: column and spacedtherefrom, and a heating wiretcarried by the jacket forheating thelsp'ace between the-jacketand theico'lumn, the improvementawhich comprisesa retaining postor'insulat ingmate'rial: rormingipart 0f thejacketwalL: the jacket having awertical slotin which-the post is seatedthe heating wire including :a plurality'of tur nsflexte'riding at'lea'st partly around'the exterior of the jacket, 'mear'is on thepost for holding. said turns in vertically spaced relation; and a 'contactfor ene gizing the wire andadjii'st'able along the-post-toen'gagedifferent turns of the wire; the post having avertical groove in its'outer face,=the turns extending across the groove,'sai d contact including a releasable "clamping device extending into the groove;

12 In-an apparatus of the 'characterdes'cribed, having a column, e heating jacket surrounding the column and spaced therefrom, and a heating Wil Cfilfi'tl bYtlle jacket f0!" heating the space betweenthejack'et and thecolum'n; the improvemerit which comprises al ietail'iing post (if insulatin material forming part 6f the I jacket Wall, the jakethaiiihg a Vertical Slot in which theDdSt is seated the heating wire including a plurality of turns extending at'lcast. partly around theexterior of the jacket, means on th'postfor holding saidturns in ve'rueanyspaced reiatioma' contact for energizing thewireand adjustable alngthe post to engagefdiilerent turns of the wire, and a draftfjacket surroundin g'the heating jackt and spaced therfrdin, the draft jacket having a vertical slotppposite .said first slot and through which the adjustable contact extends, and a slide mounted in K the draft jacket slot for supporting the contact.

. 1'3. 1 In an. apparatus oflthe characteridescribd,

having a column, a heating jacket surrounding the column and spaced therefrom, and a heating wire carried by the jacket for heating the space between the jacket and the column, the improvement which comprises a retaining post of insulating material forming part of the jacket wall, the jacket having a vertical slot in which the post is seated, the heating wire including a plurality of turns extending at least partly around the exterior of the jacket, means on the post for holding said turns in vertical spaced relation, a contact for energizing the wire and adjustable along the post to engage different turns of the wire, and a plurality of temperature indicating devices extending through the post into said space for indicating the column temperature and also the temperature difference across the space.

14. In combination with a column for fractionating, and the like, and a heating jacket surrounding the column and providing an intervening space, a device for determining temperature conditions in said space and comprising an insulating member disposed in an opening in the jacket, a thermocouple including a pair of wires extending through the insulating member and interconnected in said space, a second insulating member disposed in an opening in the jacket, a difierential thermocouple including a third wire extending through the second member into said space, a spring wire connected between said last wire and the interconnection of the first wires and acting to urge said interconnection against the column, a voltmeter connected across the first wires to indicate the column temperature, and a galvanometer connected between said third wire and one of the first wires for indicating the temperature diiferential across said space.

15. The improvement as defined in claim 7, comprising also a temperature indicating device extending through an opening in the post into said space.

16. The improvement as defined in claim 7, comprising also a temperature indicating device extending through an opening in the post into said space, and a spring connected to said device for urging the same against the column.

GEORGE A. DALIN.

REFERENCES CITED The following references are of record in the file of this patent:

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